Current transmission delay measurements are typically made by injecting a test audio signal into a test connection between a phone and a network used to transport the test audio signal. Such methods assume that the delay introduced by the telephones is quite small. This assumption is not true for voice over Internet protocol (VoIP) calls that terminate on Internet protocol (IP) telephones. Audio signals transported in VoIP networks are coded as a complex IP signal stream. For IP telephones, in order to reproduce the audio signal, the phone must process the received IP signal stream. For example, such processing may include steps to depacketize, decode, and remove jitter from the received IP signal stream. Such processing may introduce significant delay in the transmission path that cannot be ignored or accurately estimated.